French news agency AFP reports that Ernesto Mauri, the chief executive of Mondadori France, the publisher of French gossip magazine Closer, Valerie Suau, a photographer at the regional daily La Provence, and La Provence's general director, Marc Auburtin, are all under formal investigation for "breach of privacy" for allowing the photos of Duchess Kate sunbathing while on vacation to be taken and published.

Closer was the first publication to publish a five-page spread of photos of what appears to be the Duchess of Cambridge, 31, on vacation, sunbathing, under the headline "Oh My God!" in September. Other magazines quickly followed, including the Irish Daily Star, two Swedish magazines and the Italian magazine, Chi, which featured a 26-page photo spread.

La Provence published long-lens photos of both William and the duchess in swimwear, not topless. The publication denies that any of its photographers, including Suau, took the topless photos and says it "supports its journalist [Valérie Suau, the photographer] in the judicial ordeal she going through today." The paper also acknowledged that Auburtin has also been formally placed under investigation.

"There is nothing indecent about this photograph and it does not infringe upon the dignity of the prince and his wife; it had no other goal for La Provence but to inform its readers about the presence of this persons in their region."

La Provence added, "That is the reason why La Provence and its journalist [Valérie Suau] consider that they did not infringe upon the privacy of the prince and the princess and find as a consequence that the investigation under which they are placed is not justified: They will give their explanation when time comes before the court."

La Provence concluded, "For now, the newspaper La Provence and Madam Suau can only be surprised by the judicial treatment that is being given to this case: the criminal proceeding chosen by the plaintiffs and the Nanterre prosecutor's office, which has opened a criminal procedure under the authority of two instructor magistrates, appears totally disproportionate given the quite trivial photograph published by La Provence."

With the mystery of who took the topless photos still alive, the editor of Closer and other publications that posted those photos have declined to say who they purchased the photos from or how much they paid.

St. James Palace took swift legal action after the photos were published, taking Closer to court in France and winning a legal victory when the court ordered the magazine to turn over all digital copies of photos of the duchess and to not print the photos further, or face a $12,000 fine each time it defies the ruling.

Lawyers for the palace argued the royal couple was sharing a "healthy and profoundly intimate" moment when the photos were taken and that the situation was "deeply personal."

The ruling only applied to Closer in France, however, allowing the additional outlets to subsequently publish the photos.

Police in France, at the request of the royal family, also opened a criminal investigation into whether the photos were an invasion of privacy.

The decision to publish the photos cost at least one editor his job. In November, Michael O'Kane, editor of the Irish Daily Star, a tabloid newspaper published in Ireland, submitted his resignation under pressure from shareholders and a threat from the owner of the tabloid to shut it down unless he resigned.

In a statement obtained by the BBC, the Irish Daily Star wrote, "As a result of the publication … issues arose with the shareholders of Independent Star Limited. Having considered those issues in tandem with Mr O'Kane, it is Mr. O'Kane's decision to resign as editor of the Irish Daily Star."

The royal couple's lawyer declined to comment to the AFP. A representative for Mondadori France told the AFP the company, "is not aware of anything new with respect to what is already known about the issue."

Duchess Kate is now pregnant with the couple's first child and expected to give birth in July.

Buckingham Palace was forced to announce the pregnancy in December after the duchess was admitted to the hospital, where she spent four nights, for hyperemesis gravidarum, an acute morning sickness that requires supplementary hydration and nutrients, the palace said.